Illustration
Shamrock Inkberry Holly
Ilex glabra 'Shamrock'
Shamrock Inkberry Holly blooms from May through June.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Shamrock Inkberry Holly
Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 4–9. Expect it to reach about 4 ft tall and 3.5 ft wide at maturity, in roughly 5 years (a house reading).
Is Shamrock Inkberry Holly toxic to dogs or cats?
- Listed as toxic to dogs and cats by Pet Poison Helpline.
Lists differ and none is complete. If a pet eats a plant and seems unwell, call a veterinarian or a pet poison helpline.
What was checked
Nine facts were checked against named botanical sources, each recorded beside the sources that carried it: mature height and spread, hardiness zones, sun, water, bloom months and color, the trait tags, and years to mature size, which rests on a recorded house rule where no publisher states one and is marked so. Soil, diseases, pests, toxicity and the plant's own names have not yet been read for this plant, and its trait tags are the ones a feature uses rather than every word a page prints. Each fact above carries its own mark. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.
When to plant Shamrock Inkberry Holly
Plant Shamrock Inkberry Holly in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. In zone 6, the middle of its hardy zones 4 to 9, spring means March to May and fall means August or September. Once settled, it blooms from May to June.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 6, the middle of this plant's hardy range, start with zone 6 in March. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Shamrock Inkberry Holly get?
4 fttall5 ft 7 inan adult3.5 ftwideSee Shamrock Inkberry Holly in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant Shamrock Inkberry Holly
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Space Shamrock Inkberry Holly about 3.5 ft apart, center to center, so each plant has room to reach its full width.
Add Shamrock Inkberry Holly to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Where these facts come from
Shamrock Inkberry Holly's height, spread, hardiness zones, sun, water, bloom months and color and trait tags were checked against 10 published sources on October 20, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.
- Missouri Botanical Gardenheight, spread, hardiness zones, sun, water, bloom months and color and trait tags
- Plant Addictsheight, spread, hardiness zones, sun, water and trait tags
- NC State Extensionheight, water, bloom months and color and trait tags
- Pleasant Run Nurseryheight, spread, hardiness zones and sun
- Missouri Botanical Gardenspecies template controlwater and bloom months and color
- Oregon State Universityheight, hardiness zones and sun
- RHSRoyal Horticultural Societywater and bloom months and color
- tankardnurseries.comTankard Nurseriesheight, spread and hardiness zones
- University of Illinois Extensionheight
- woodyplants.cals.cornell.eduCornell Universityheight
How the checking works, and what each standard covers, is on the verified plants page.
Where it grows wild
A garden form of Ilex glabra
Its wild parent is native to 20 states and 1 province.
United States: Alabama, Arkansas, Connecticut, Delaware, Florida, Georgia, Louisiana, Maine, Maryland, Massachusetts, Mississippi, New Hampshire, New Jersey, New York, North Carolina, Pennsylvania, Rhode Island, South Carolina, Texas, Virginia and 8 more
Canada: Nova Scotia
Range data from the World Checklist of Vascular Plants, Royal Botanic Gardens, Kew (CC BY 4.0, adapted) and USDA PLANTS. How the native range is credited.
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Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.